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Subject[PATCH 5.2 18/61] perf header: Assign proper ff->ph in perf_event__synthesize_features()
Date
From: Song Liu <songliubraving@fb.com>

commit c952b35f4b15dd1b83e952718dec3307256383ef upstream.

bpf/btf write_* functions need ff->ph->env.

With this missing, pipe-mode (perf record -o -) would crash like:

Program terminated with signal SIGSEGV, Segmentation fault.

This patch assign proper ph value to ff.

Committer testing:

(gdb) run record -o -
Starting program: /root/bin/perf record -o -
PERFILE2
<SNIP start of perf.data headers>
Thread 1 "perf" received signal SIGSEGV, Segmentation fault.
__do_write_buf (size=4, buf=0x160, ff=0x7fffffff8f80) at util/header.c:126
126 memcpy(ff->buf + ff->offset, buf, size);
(gdb) bt
#0 __do_write_buf (size=4, buf=0x160, ff=0x7fffffff8f80) at util/header.c:126
#1 do_write (ff=ff@entry=0x7fffffff8f80, buf=buf@entry=0x160, size=4) at util/header.c:137
#2 0x00000000004eddba in write_bpf_prog_info (ff=0x7fffffff8f80, evlist=<optimized out>) at util/header.c:912
#3 0x00000000004f69d7 in perf_event__synthesize_features (tool=tool@entry=0x97cc00 <record>, session=session@entry=0x7fffe9c6d010,
evlist=0x7fffe9cae010, process=process@entry=0x4435d0 <process_synthesized_event>) at util/header.c:3695
#4 0x0000000000443c79 in record__synthesize (tail=tail@entry=false, rec=0x97cc00 <record>) at builtin-record.c:1214
#5 0x0000000000444ec9 in __cmd_record (rec=0x97cc00 <record>, argv=<optimized out>, argc=0) at builtin-record.c:1435
#6 cmd_record (argc=0, argv=<optimized out>) at builtin-record.c:2450
#7 0x00000000004ae3e9 in run_builtin (p=p@entry=0x98e058 <commands+216>, argc=argc@entry=3, argv=0x7fffffffd670) at perf.c:304
#8 0x000000000042eded in handle_internal_command (argv=<optimized out>, argc=<optimized out>) at perf.c:356
#9 run_argv (argcp=<optimized out>, argv=<optimized out>) at perf.c:400
#10 main (argc=3, argv=<optimized out>) at perf.c:522
(gdb)

After the patch the SEGSEGV is gone.

Reported-by: David Carrillo Cisneros <davidca@fb.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: kernel-team@fb.com
Cc: stable@vger.kernel.org # v5.1+
Fixes: 606f972b1361 ("perf bpf: Save bpf_prog_info information as headers to perf.data")
Link: http://lkml.kernel.org/r/20190620010453.4118689-1-songliubraving@fb.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
tools/perf/util/header.c | 1 +
1 file changed, 1 insertion(+)

--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -3602,6 +3602,7 @@ int perf_event__synthesize_features(stru
return -ENOMEM;

ff.size = sz - sz_hdr;
+ ff.ph = &session->header;

for_each_set_bit(feat, header->adds_features, HEADER_FEAT_BITS) {
if (!feat_ops[feat].synthesize) {

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